1. Field of the Invention
The present invention relates generally to methods and apparatuses for use in substrate processing. More specifically, the present invention relates to plasma monitoring methods and apparatuses for use in substrate processing using different processes, such as a plasma nitridation process and others.
2. Description of the Related Art
Integrated circuits have evolved into complex devices that can include millions of components (e.g., transistors, capacitors, resistors, and the like) on a single chip. The evolution of chip designs continually requires faster circuitry and greater circuit density. The demands for greater circuit density necessitate a reduction in the dimensions of the integrated circuit components. The minimal dimensions of features of such devices are commonly referred to in the art as critical dimensions. The critical dimensions generally include the minimal widths of the features, such as lines, columns, openings, spaces between the lines, and device/film thickness and the like. As these critical dimensions shrink, accurate measurement and process control becomes more difficult.
Importantly, in some cases, monitoring of implantation processes and controlling material thickness remain to be a challenge in substrate device processing. For example, one problem associated with a conventional plasma process used in the manufacture of substrates is the lack of an ability to accurately monitor the formation of plasma and thereby accurately controlling the plasma state in a plasma chamber operating with lower powers. One known method used to control a process attempts to achieve optimum power in a chamber by using a match circuit to transform the impedance of the plasma to a value that equals or matches the characteristic impedance of the line through which RF power is delivered to the chamber. At the match point, optimum power is delivered into the plasma and little power is reflected back toward the RF supply. In this method, tuning the match circuit, which is controlled by a detector, is accomplished by varying the variable reactance elements within the match circuit based on the power detected by a detector. Unfortunately, the impedance of plasma is a complex and highly variable function of many process parameters and thus requires constant monitoring and adjustment by the detector. In addition, in some cases, the generator may not be capable of controlling lower powers and thus the plasma may fluctuate during substrate processing.
Therefore, there is a need in the art for an improved method and apparatus for substrate monitoring and process control during the manufacture of integrated circuits.